Back-port fixes for b/62196835
Bug: 62196835
Test: Created an accessibility service that displays a system
and a toast overlay, confirmed that it disappeared when we
reached the accessibility permission screen that uses this
flag.
Change-Id: Ic51ead670fc480e549512ba1d02f49d9c13bc3f0
(cherry picked from commit 41ff5389daa6e6ce4aa853bfae96e5ced0b1d8df)